Table 1.

Anti-inflammatory activities and mechanism of usnic acid.

Model	Mechanism or Effect	Concentration	Year	References
Acute and chronic inflammation rat models	Reduce the swelling of rat foot induced by carrageenan in dose dependent. Only effect at 100 mg/kg.	25 mg/kg, 50 mg/kg, 100 mg/kg, p.o.	2000	[18]
Lipopolysaccharide (LPS) activated RAW264.7 macrophages	Inhibit the express of TNF-α and iNOS, possibly through suppression of nuclear translocation of NF-κB p65 and I-κBα degradation; Inhibit LPS-induced TNF-α accumulation and NO production in a dose-dependent manner.	0.5–400 μM; IC50: 4.7 μM (TNF-α), 12.8 μM (NO)	2008	[59]
Lipopolysaccharide (LPS) activated RAW264.7 macrophages	Down-regulating iNOS, COX-2, IL-1β, IL-6 and TNF-α, COX-2 gene expression through the suppression of NF-κB activation and increasing anti-inflammatory cytokine IL-10 and anti-inflammatory mediator HO-1 production.	10 μg/mL, 50 μg/mL and 100 μg/mL	2011	[60]
1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced Parkinson’s disease model in Male C57BL/6 mice	Inhibit MPP+-induced glial activation in primary astrocytes by blocking NF-κB activation.	5 or 25 mg/kg dissolved in phosphate buffered saline (PBS) containing 5% Tween-80 (i.p.)	2020	[61]
Tau protein derived hexapeptide AcPHF6 model	Inhibit the aggregation of full-length 2N4R tau protein by a heparin-induced mechanism.	10 μM	2020	[62] *
Human neuroblastoma SK-N-SH cell line (SH-SY5Y)	Exert no significant hepatotoxicity, showed low hepatotoxicity at 40 μM.	10–40 μM	2020	[62] *
Human hepatocyte cells (LO2) cells	Exert no significant hepatotoxicity, showed low hepatotoxicity at 40 μM.	10–40 μM	2020	[62] *
Murine microglial BV2 cells	Reduce NO release in Lipopolysaccharide-stimulated mouse microglia BV2 cells.	10–40 μM	2020	[62] *
Adult male SD rats	Enhance the cognitive ability of okadiac acid induced AD model rats.	5 mg/kg, 10 mg/kg	2020	[62] *

*: Usnic acid derivatives, synthesized from the reaction of usnic acid with the corresponding hydrazines and hydrazides.